/*
 * Copyright 2002-2019 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.feilong.lib.springframework.util;

import java.lang.reflect.Array;
import java.util.Arrays;
import java.util.Collection;
import java.util.Map;

/**
 * Miscellaneous object utility methods.
 *
 * <p>
 * Mainly for internal use within the framework.
 *
 * <p>
 * Thanks to Alex Ruiz for contributing several enhancements to this class!
 *
 * @author Juergen Hoeller
 * @author Keith Donald
 * @author Rod Johnson
 * @author Rob Harrop
 * @author Chris Beams
 * @author Sam Brannen
 * @since 19.03.2004
 * @see ClassUtils
 * @see CollectionUtils
 * @see StringUtils
 */
public abstract class ObjectUtils{

    private static final int    INITIAL_HASH            = 7;

    private static final int    MULTIPLIER              = 31;

    private static final String EMPTY_STRING            = "";

    private static final String NULL_STRING             = "null";

    private static final String ARRAY_START             = "{";

    private static final String ARRAY_END               = "}";

    private static final String EMPTY_ARRAY             = ARRAY_START + ARRAY_END;

    private static final String ARRAY_ELEMENT_SEPARATOR = ", ";

    /**
     * Determine whether the given array is empty:
     * i.e. {@code null} or of zero length.
     * 
     * @param array
     *            the array to check
     * @see #isEmpty(Object)
     */
    public static boolean isEmpty(Object[] array){
        return (array == null || array.length == 0);
    }

    /**
     * Determine whether the given object is empty.
     * <p>
     * This method supports the following object types.
     * <ul>
     * <li>{@code Array}: considered empty if its length is zero</li>
     * <li>{@link CharSequence}: considered empty if its length is zero</li>
     * <li>{@link Collection}: delegates to {@link Collection#isEmpty()}</li>
     * <li>{@link Map}: delegates to {@link Map#isEmpty()}</li>
     * </ul>
     * <p>
     * If the given object is non-null and not one of the aforementioned
     * supported types, this method returns {@code false}.
     * 
     * @param obj
     *            the object to check
     * @return {@code true} if the object is {@code null} or <em>empty</em>
     * @since 4.2
     * @see ObjectUtils#isEmpty(Object[])
     */
    @SuppressWarnings("rawtypes")
    public static boolean isEmpty(Object obj){
        if (obj == null){
            return true;
        }

        if (obj instanceof CharSequence){
            return ((CharSequence) obj).length() == 0;
        }
        if (obj.getClass().isArray()){
            return Array.getLength(obj) == 0;
        }
        if (obj instanceof Collection){
            return ((Collection) obj).isEmpty();
        }
        if (obj instanceof Map){
            return ((Map) obj).isEmpty();
        }

        // else
        return false;
    }

    /**
     * Check whether the given array of enum constants contains a constant with the given name,
     * ignoring case when determining a match.
     * 
     * @param enumValues
     *            the enum values to check, typically obtained via {@code MyEnum.values()}
     * @param constant
     *            the constant name to find (must not be null or empty string)
     * @return whether the constant has been found in the given array
     */
    public static boolean containsConstant(Enum<?>[] enumValues,String constant){
        return containsConstant(enumValues, constant, false);
    }

    /**
     * Check whether the given array of enum constants contains a constant with the given name.
     * 
     * @param enumValues
     *            the enum values to check, typically obtained via {@code MyEnum.values()}
     * @param constant
     *            the constant name to find (must not be null or empty string)
     * @param caseSensitive
     *            whether case is significant in determining a match
     * @return whether the constant has been found in the given array
     */
    public static boolean containsConstant(Enum<?>[] enumValues,String constant,boolean caseSensitive){
        for (Enum<?> candidate : enumValues){
            if (caseSensitive ? candidate.toString().equals(constant) : candidate.toString().equalsIgnoreCase(constant)){
                return true;
            }
        }
        return false;
    }

    //---------------------------------------------------------------------
    // Convenience methods for content-based equality/hash-code handling
    //---------------------------------------------------------------------

    /**
     * Determine if the given objects are equal, returning {@code true} if
     * both are {@code null} or {@code false} if only one is {@code null}.
     * <p>
     * Compares arrays with {@code Arrays.equals}, performing an equality
     * check based on the array elements rather than the array reference.
     * 
     * @param o1
     *            first Object to compare
     * @param o2
     *            second Object to compare
     * @return whether the given objects are equal
     * @see Object#equals(Object)
     * @see java.util.Arrays#equals
     */
    public static boolean nullSafeEquals(Object o1,Object o2){
        if (o1 == o2){
            return true;
        }
        if (o1 == null || o2 == null){
            return false;
        }
        if (o1.equals(o2)){
            return true;
        }
        if (o1.getClass().isArray() && o2.getClass().isArray()){
            return arrayEquals(o1, o2);
        }
        return false;
    }

    /**
     * Compare the given arrays with {@code Arrays.equals}, performing an equality
     * check based on the array elements rather than the array reference.
     * 
     * @param o1
     *            first array to compare
     * @param o2
     *            second array to compare
     * @return whether the given objects are equal
     * @see #nullSafeEquals(Object, Object)
     * @see java.util.Arrays#equals
     */
    private static boolean arrayEquals(Object o1,Object o2){
        if (o1 instanceof Object[] && o2 instanceof Object[]){
            return Arrays.equals((Object[]) o1, (Object[]) o2);
        }
        if (o1 instanceof boolean[] && o2 instanceof boolean[]){
            return Arrays.equals((boolean[]) o1, (boolean[]) o2);
        }
        if (o1 instanceof byte[] && o2 instanceof byte[]){
            return Arrays.equals((byte[]) o1, (byte[]) o2);
        }
        if (o1 instanceof char[] && o2 instanceof char[]){
            return Arrays.equals((char[]) o1, (char[]) o2);
        }
        if (o1 instanceof double[] && o2 instanceof double[]){
            return Arrays.equals((double[]) o1, (double[]) o2);
        }
        if (o1 instanceof float[] && o2 instanceof float[]){
            return Arrays.equals((float[]) o1, (float[]) o2);
        }
        if (o1 instanceof int[] && o2 instanceof int[]){
            return Arrays.equals((int[]) o1, (int[]) o2);
        }
        if (o1 instanceof long[] && o2 instanceof long[]){
            return Arrays.equals((long[]) o1, (long[]) o2);
        }
        if (o1 instanceof short[] && o2 instanceof short[]){
            return Arrays.equals((short[]) o1, (short[]) o2);
        }
        return false;
    }

    /**
     * Return as hash code for the given object; typically the value of
     * {@code Object#hashCode()}}. If the object is an array,
     * this method will delegate to any of the {@code nullSafeHashCode}
     * methods for arrays in this class. If the object is {@code null},
     * this method returns 0.
     * 
     * @see Object#hashCode()
     * @see #nullSafeHashCode(Object[])
     * @see #nullSafeHashCode(boolean[])
     * @see #nullSafeHashCode(byte[])
     * @see #nullSafeHashCode(char[])
     * @see #nullSafeHashCode(double[])
     * @see #nullSafeHashCode(float[])
     * @see #nullSafeHashCode(int[])
     * @see #nullSafeHashCode(long[])
     * @see #nullSafeHashCode(short[])
     */
    public static int nullSafeHashCode(Object obj){
        if (obj == null){
            return 0;
        }
        if (obj.getClass().isArray()){
            if (obj instanceof Object[]){
                return nullSafeHashCode((Object[]) obj);
            }
            if (obj instanceof boolean[]){
                return nullSafeHashCode((boolean[]) obj);
            }
            if (obj instanceof byte[]){
                return nullSafeHashCode((byte[]) obj);
            }
            if (obj instanceof char[]){
                return nullSafeHashCode((char[]) obj);
            }
            if (obj instanceof double[]){
                return nullSafeHashCode((double[]) obj);
            }
            if (obj instanceof float[]){
                return nullSafeHashCode((float[]) obj);
            }
            if (obj instanceof int[]){
                return nullSafeHashCode((int[]) obj);
            }
            if (obj instanceof long[]){
                return nullSafeHashCode((long[]) obj);
            }
            if (obj instanceof short[]){
                return nullSafeHashCode((short[]) obj);
            }
        }
        return obj.hashCode();
    }

    /**
     * Return a hash code based on the contents of the specified array.
     * If {@code array} is {@code null}, this method returns 0.
     */
    public static int nullSafeHashCode(Object[] array){
        if (array == null){
            return 0;
        }
        int hash = INITIAL_HASH;
        for (Object element : array){
            hash = MULTIPLIER * hash + nullSafeHashCode(element);
        }
        return hash;
    }

    /**
     * Return a hash code based on the contents of the specified array.
     * If {@code array} is {@code null}, this method returns 0.
     */
    public static int nullSafeHashCode(boolean[] array){
        if (array == null){
            return 0;
        }
        int hash = INITIAL_HASH;
        for (boolean element : array){
            hash = MULTIPLIER * hash + hashCode(element);
        }
        return hash;
    }

    /**
     * Return a hash code based on the contents of the specified array.
     * If {@code array} is {@code null}, this method returns 0.
     */
    public static int nullSafeHashCode(byte[] array){
        if (array == null){
            return 0;
        }
        int hash = INITIAL_HASH;
        for (byte element : array){
            hash = MULTIPLIER * hash + element;
        }
        return hash;
    }

    /**
     * Return a hash code based on the contents of the specified array.
     * If {@code array} is {@code null}, this method returns 0.
     */
    public static int nullSafeHashCode(char[] array){
        if (array == null){
            return 0;
        }
        int hash = INITIAL_HASH;
        for (char element : array){
            hash = MULTIPLIER * hash + element;
        }
        return hash;
    }

    /**
     * Return a hash code based on the contents of the specified array.
     * If {@code array} is {@code null}, this method returns 0.
     */
    public static int nullSafeHashCode(double[] array){
        if (array == null){
            return 0;
        }
        int hash = INITIAL_HASH;
        for (double element : array){
            hash = MULTIPLIER * hash + hashCode(element);
        }
        return hash;
    }

    /**
     * Return a hash code based on the contents of the specified array.
     * If {@code array} is {@code null}, this method returns 0.
     */
    public static int nullSafeHashCode(float[] array){
        if (array == null){
            return 0;
        }
        int hash = INITIAL_HASH;
        for (float element : array){
            hash = MULTIPLIER * hash + hashCode(element);
        }
        return hash;
    }

    /**
     * Return a hash code based on the contents of the specified array.
     * If {@code array} is {@code null}, this method returns 0.
     */
    public static int nullSafeHashCode(int[] array){
        if (array == null){
            return 0;
        }
        int hash = INITIAL_HASH;
        for (int element : array){
            hash = MULTIPLIER * hash + element;
        }
        return hash;
    }

    /**
     * Return a hash code based on the contents of the specified array.
     * If {@code array} is {@code null}, this method returns 0.
     */
    public static int nullSafeHashCode(long[] array){
        if (array == null){
            return 0;
        }
        int hash = INITIAL_HASH;
        for (long element : array){
            hash = MULTIPLIER * hash + hashCode(element);
        }
        return hash;
    }

    /**
     * Return a hash code based on the contents of the specified array.
     * If {@code array} is {@code null}, this method returns 0.
     */
    public static int nullSafeHashCode(short[] array){
        if (array == null){
            return 0;
        }
        int hash = INITIAL_HASH;
        for (short element : array){
            hash = MULTIPLIER * hash + element;
        }
        return hash;
    }

    /**
     * Return the same value as {@link Boolean#hashCode()}}.
     * 
     * @see Boolean#hashCode()
     */
    public static int hashCode(boolean bool){
        return (bool ? 1231 : 1237);
    }

    /**
     * Return the same value as {@link Double#hashCode()}}.
     * 
     * @see Double#hashCode()
     */
    public static int hashCode(double dbl){
        return hashCode(Double.doubleToLongBits(dbl));
    }

    /**
     * Return the same value as {@link Float#hashCode()}}.
     * 
     * @see Float#hashCode()
     */
    public static int hashCode(float flt){
        return Float.floatToIntBits(flt);
    }

    /**
     * Return the same value as {@link Long#hashCode()}}.
     * 
     * @see Long#hashCode()
     */
    public static int hashCode(long lng){
        return (int) (lng ^ (lng >>> 32));
    }

    //---------------------------------------------------------------------
    // Convenience methods for toString output
    //---------------------------------------------------------------------

    /**
     * Return a String representation of an object's overall identity.
     * 
     * @param obj
     *            the object (may be {@code null})
     * @return the object's identity as String representation,
     *         or an empty String if the object was {@code null}
     */
    public static String identityToString(Object obj){
        if (obj == null){
            return EMPTY_STRING;
        }
        return obj.getClass().getName() + "@" + getIdentityHexString(obj);
    }

    /**
     * Return a hex String form of an object's identity hash code.
     * 
     * @param obj
     *            the object
     * @return the object's identity code in hex notation
     */
    public static String getIdentityHexString(Object obj){
        return Integer.toHexString(System.identityHashCode(obj));
    }

    /**
     * Return a content-based String representation if {@code obj} is
     * not {@code null}; otherwise returns an empty String.
     * <p>
     * Differs from {@link #nullSafeToString(Object)} in that it returns
     * an empty String rather than "null" for a {@code null} value.
     * 
     * @param obj
     *            the object to build a display String for
     * @return a display String representation of {@code obj}
     * @see #nullSafeToString(Object)
     */
    public static String getDisplayString(Object obj){
        if (obj == null){
            return EMPTY_STRING;
        }
        return nullSafeToString(obj);
    }

    /**
     * Determine the class name for the given object.
     * <p>
     * Returns a {@code "null"} String if {@code obj} is {@code null}.
     * 
     * @param obj
     *            the object to introspect (may be {@code null})
     * @return the corresponding class name
     */
    public static String nullSafeClassName(Object obj){
        return (obj != null ? obj.getClass().getName() : NULL_STRING);
    }

    /**
     * Return a String representation of the specified Object.
     * <p>
     * Builds a String representation of the contents in case of an array.
     * Returns a {@code "null"} String if {@code obj} is {@code null}.
     * 
     * @param obj
     *            the object to build a String representation for
     * @return a String representation of {@code obj}
     */
    public static String nullSafeToString(Object obj){
        if (obj == null){
            return NULL_STRING;
        }
        if (obj instanceof String){
            return (String) obj;
        }
        if (obj instanceof Object[]){
            return nullSafeToString((Object[]) obj);
        }
        if (obj instanceof boolean[]){
            return nullSafeToString((boolean[]) obj);
        }
        if (obj instanceof byte[]){
            return nullSafeToString((byte[]) obj);
        }
        if (obj instanceof char[]){
            return nullSafeToString((char[]) obj);
        }
        if (obj instanceof double[]){
            return nullSafeToString((double[]) obj);
        }
        if (obj instanceof float[]){
            return nullSafeToString((float[]) obj);
        }
        if (obj instanceof int[]){
            return nullSafeToString((int[]) obj);
        }
        if (obj instanceof long[]){
            return nullSafeToString((long[]) obj);
        }
        if (obj instanceof short[]){
            return nullSafeToString((short[]) obj);
        }
        String str = obj.toString();
        return (str != null ? str : EMPTY_STRING);
    }

    /**
     * Return a String representation of the contents of the specified array.
     * <p>
     * The String representation consists of a list of the array's elements,
     * enclosed in curly braces ({@code "{}"}). Adjacent elements are separated
     * by the characters {@code ", "} (a comma followed by a space).
     * Returns a {@code "null"} String if {@code array} is {@code null}.
     * 
     * @param array
     *            the array to build a String representation for
     * @return a String representation of {@code array}
     */
    public static String nullSafeToString(Object[] array){
        if (array == null){
            return NULL_STRING;
        }
        int length = array.length;
        if (length == 0){
            return EMPTY_ARRAY;
        }
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < length; i++){
            if (i == 0){
                sb.append(ARRAY_START);
            }else{
                sb.append(ARRAY_ELEMENT_SEPARATOR);
            }
            sb.append(String.valueOf(array[i]));
        }
        sb.append(ARRAY_END);
        return sb.toString();
    }

    /**
     * Return a String representation of the contents of the specified array.
     * <p>
     * The String representation consists of a list of the array's elements,
     * enclosed in curly braces ({@code "{}"}). Adjacent elements are separated
     * by the characters {@code ", "} (a comma followed by a space).
     * Returns a {@code "null"} String if {@code array} is {@code null}.
     * 
     * @param array
     *            the array to build a String representation for
     * @return a String representation of {@code array}
     */
    public static String nullSafeToString(boolean[] array){
        if (array == null){
            return NULL_STRING;
        }
        int length = array.length;
        if (length == 0){
            return EMPTY_ARRAY;
        }
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < length; i++){
            if (i == 0){
                sb.append(ARRAY_START);
            }else{
                sb.append(ARRAY_ELEMENT_SEPARATOR);
            }

            sb.append(array[i]);
        }
        sb.append(ARRAY_END);
        return sb.toString();
    }

    /**
     * Return a String representation of the contents of the specified array.
     * <p>
     * The String representation consists of a list of the array's elements,
     * enclosed in curly braces ({@code "{}"}). Adjacent elements are separated
     * by the characters {@code ", "} (a comma followed by a space).
     * Returns a {@code "null"} String if {@code array} is {@code null}.
     * 
     * @param array
     *            the array to build a String representation for
     * @return a String representation of {@code array}
     */
    public static String nullSafeToString(byte[] array){
        if (array == null){
            return NULL_STRING;
        }
        int length = array.length;
        if (length == 0){
            return EMPTY_ARRAY;
        }
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < length; i++){
            if (i == 0){
                sb.append(ARRAY_START);
            }else{
                sb.append(ARRAY_ELEMENT_SEPARATOR);
            }
            sb.append(array[i]);
        }
        sb.append(ARRAY_END);
        return sb.toString();
    }

    /**
     * Return a String representation of the contents of the specified array.
     * <p>
     * The String representation consists of a list of the array's elements,
     * enclosed in curly braces ({@code "{}"}). Adjacent elements are separated
     * by the characters {@code ", "} (a comma followed by a space).
     * Returns a {@code "null"} String if {@code array} is {@code null}.
     * 
     * @param array
     *            the array to build a String representation for
     * @return a String representation of {@code array}
     */
    public static String nullSafeToString(char[] array){
        if (array == null){
            return NULL_STRING;
        }
        int length = array.length;
        if (length == 0){
            return EMPTY_ARRAY;
        }
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < length; i++){
            if (i == 0){
                sb.append(ARRAY_START);
            }else{
                sb.append(ARRAY_ELEMENT_SEPARATOR);
            }
            sb.append("'").append(array[i]).append("'");
        }
        sb.append(ARRAY_END);
        return sb.toString();
    }

    /**
     * Return a String representation of the contents of the specified array.
     * <p>
     * The String representation consists of a list of the array's elements,
     * enclosed in curly braces ({@code "{}"}). Adjacent elements are separated
     * by the characters {@code ", "} (a comma followed by a space).
     * Returns a {@code "null"} String if {@code array} is {@code null}.
     * 
     * @param array
     *            the array to build a String representation for
     * @return a String representation of {@code array}
     */
    public static String nullSafeToString(double[] array){
        if (array == null){
            return NULL_STRING;
        }
        int length = array.length;
        if (length == 0){
            return EMPTY_ARRAY;
        }
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < length; i++){
            if (i == 0){
                sb.append(ARRAY_START);
            }else{
                sb.append(ARRAY_ELEMENT_SEPARATOR);
            }

            sb.append(array[i]);
        }
        sb.append(ARRAY_END);
        return sb.toString();
    }

    /**
     * Return a String representation of the contents of the specified array.
     * <p>
     * The String representation consists of a list of the array's elements,
     * enclosed in curly braces ({@code "{}"}). Adjacent elements are separated
     * by the characters {@code ", "} (a comma followed by a space).
     * Returns a {@code "null"} String if {@code array} is {@code null}.
     * 
     * @param array
     *            the array to build a String representation for
     * @return a String representation of {@code array}
     */
    public static String nullSafeToString(float[] array){
        if (array == null){
            return NULL_STRING;
        }
        int length = array.length;
        if (length == 0){
            return EMPTY_ARRAY;
        }
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < length; i++){
            if (i == 0){
                sb.append(ARRAY_START);
            }else{
                sb.append(ARRAY_ELEMENT_SEPARATOR);
            }

            sb.append(array[i]);
        }
        sb.append(ARRAY_END);
        return sb.toString();
    }

    /**
     * Return a String representation of the contents of the specified array.
     * <p>
     * The String representation consists of a list of the array's elements,
     * enclosed in curly braces ({@code "{}"}). Adjacent elements are separated
     * by the characters {@code ", "} (a comma followed by a space).
     * Returns a {@code "null"} String if {@code array} is {@code null}.
     * 
     * @param array
     *            the array to build a String representation for
     * @return a String representation of {@code array}
     */
    public static String nullSafeToString(int[] array){
        if (array == null){
            return NULL_STRING;
        }
        int length = array.length;
        if (length == 0){
            return EMPTY_ARRAY;
        }
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < length; i++){
            if (i == 0){
                sb.append(ARRAY_START);
            }else{
                sb.append(ARRAY_ELEMENT_SEPARATOR);
            }
            sb.append(array[i]);
        }
        sb.append(ARRAY_END);
        return sb.toString();
    }

    /**
     * Return a String representation of the contents of the specified array.
     * <p>
     * The String representation consists of a list of the array's elements,
     * enclosed in curly braces ({@code "{}"}). Adjacent elements are separated
     * by the characters {@code ", "} (a comma followed by a space).
     * Returns a {@code "null"} String if {@code array} is {@code null}.
     * 
     * @param array
     *            the array to build a String representation for
     * @return a String representation of {@code array}
     */
    public static String nullSafeToString(long[] array){
        if (array == null){
            return NULL_STRING;
        }
        int length = array.length;
        if (length == 0){
            return EMPTY_ARRAY;
        }
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < length; i++){
            if (i == 0){
                sb.append(ARRAY_START);
            }else{
                sb.append(ARRAY_ELEMENT_SEPARATOR);
            }
            sb.append(array[i]);
        }
        sb.append(ARRAY_END);
        return sb.toString();
    }

    /**
     * Return a String representation of the contents of the specified array.
     * <p>
     * The String representation consists of a list of the array's elements,
     * enclosed in curly braces ({@code "{}"}). Adjacent elements are separated
     * by the characters {@code ", "} (a comma followed by a space).
     * Returns a {@code "null"} String if {@code array} is {@code null}.
     * 
     * @param array
     *            the array to build a String representation for
     * @return a String representation of {@code array}
     */
    public static String nullSafeToString(short[] array){
        if (array == null){
            return NULL_STRING;
        }
        int length = array.length;
        if (length == 0){
            return EMPTY_ARRAY;
        }
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < length; i++){
            if (i == 0){
                sb.append(ARRAY_START);
            }else{
                sb.append(ARRAY_ELEMENT_SEPARATOR);
            }
            sb.append(array[i]);
        }
        sb.append(ARRAY_END);
        return sb.toString();
    }

}
